. The book of photography; practical, theoretical and applied. Fig. 714,—POLARISER. to J in. ; with high-angle lenses it is notpossible to secure a perfectly dark groundbecause they take up some of the obliquerays. A photograph of diatoms taken inthis way is shown in one of the Fig. 715.— Principle of the Polariscope. The polariscope used with the micro-scope is in two parts; the polarisermounted in a sleeve to slide into the tubebeloAV the stage or into the substage (), and the analyser mounted in a tubeto fit over the objective or eyepiece (). Both the polar
. The book of photography; practical, theoretical and applied. Fig. 714,—POLARISER. to J in. ; with high-angle lenses it is notpossible to secure a perfectly dark groundbecause they take up some of the obliquerays. A photograph of diatoms taken inthis way is shown in one of the Fig. 715.— Principle of the Polariscope. The polariscope used with the micro-scope is in two parts; the polarisermounted in a sleeve to slide into the tubebeloAV the stage or into the substage (), and the analyser mounted in a tubeto fit over the objective or eyepiece (). Both the polariser and analyser con-sist of what is known as a Nicols prism,that is, a natural crystal of Iceland sparwhich has been cut in a plane lying be-tween its obtuse angles, m, n, o, p (), and the faces polished and cementedtogether in their original position with Canada balsam. It is well known thatwhen a beam of light is passed through anordinary crystal of Iceland spar it isseparated or refracted into two distinctbeams of equal brilliancy, the crystal
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectphotography, bookyear
